What's the difference between a clutch master and a brake master?

Or are there any?

Size and dual circuits?

If talking aftermarket (tilton, wilwood), they are interchangeable as long as you have done your homework with stroke and diameter afaik.

Size and dual circuits?

^ Just that. No other difference really. Clutch masters are slightly more likely to have remote reservoirs as well, some of them even have their hydraulic output lines 'hard mounted' (i.e. not removable with line fittings, just crimped or pinned on) and they are also slightly more likely to be mounted way off level so that they can't be bled properly unless bench bled first? Minor stuff aside from the two main things thatsnowinnebago mentioned. 

In reply to thatcherr :

This is not true. The part numbers for Girling, Lockheed(AP) Willwood and Tilton are all the same for a clutch or a brake master cylinder. Some very old brake masters, IE for a car with drum brakes, have a residual pressure valve that needs to be removed if using for a clutch or a disc brake.

I have had the same thought process. It seems like an adjustable bias dual master setup could easily be fabricated with two clutch masters.

thatsnowinnebago (Forum Supporter) said:

Size and dual circuits?

So you're saying if I build a dual engine AWD car I should use a brake master on the clutch pedal?

MrJoshua said:

I have had the same thought process. It seems like an adjustable bias dual master setup could easily be fabricated with two clutch masters.

Really it came up for me because I happened to look up the wilwood masters that came on my f440 chassis brake circuits and they are listed as a clutch master. But yeah, the chassis is setup exactly like this, one clutch master for the rear brakes and one for the front. The pedal is connected to a bar that pushes both plungers, but you can adjust the nut on the plunger to say which master engages earlier. 

I think it's a bit crude and there are probably better designs, but what you described is basically exactly what I happen to have. 

TurnerX19 said:

In reply to thatcherr :

This is not true. The part numbers for Girling, Lockheed(AP) Willwood and Tilton are all the same for a clutch or a brake master cylinder. Some very old brake masters, IE for a car with drum brakes, have a residual pressure valve that needs to be removed if using for a clutch or a disc brake.

What he said.  ^^

It rarely works out but when I can, I design race car clutch systems so they use the same master as the brakes so that you only have to have one spare master in the trailer.

Robbie (Forum Supporter) said:

MrJoshua said:

I have had the same thought process. It seems like an adjustable bias dual master setup could easily be fabricated with two clutch masters.

Really it came up for me because I happened to look up the wilwood masters that came on my f440 chassis brake circuits and they are listed as a clutch master. But yeah, the chassis is setup exactly like this, one clutch master for the rear brakes and one for the front. The pedal is connected to a bar that pushes both plungers, but you can adjust the nut on the plunger to say which master engages earlier. 

I think it's a bit crude and there are probably better designs, but what you described is basically exactly what I happen to have. 

That's a decent way of doing brake proportioning with a balance bar - if you're always stopping at maximum decel. Works for race cars. You can also adjust overall balance by playing with the relative sizes of the two masters. 

The last time I looked, some people were still using the old Girling single cylinder from the olden English days.  I was a bit shocked to see that familiar old stamped tin lid on my Jeep Commanche pickup, after I pulled the rubber boot off the top.

Keep looking, you'll find Lucas parts. I'm not kidding. 

I would trust a (properly sized) brake master for clutch duty, but depending on the clutch master, I wouldn't use it the other way around.  Brakes can generate up to 3000 psi.  Clutches don't need that much, and some clutch masters are designed with that in mind.  Both of the clutch masters in my cars right now are plastic.

One disengages the clutch and the other applies the brakes.  Seems like a rather important difference.

In reply to ProDarwin :

You are my kind of smartass